The K-Mets got on the board first when Champ Stuart walked to lead off the game, advanced to second on a wild pitch and to third on a Jeff McNeil single, and was knocked home by Victor Cruzado.
After the opening run the P-Rays pitching staff held Kingsport scoreless until the seventh, when Amed Rosario blasted a solo homer.
Richie Rodriguez added a solo shot of his own in the ninth but it was too little, too late for the K-Mets (16-14).
Jesus Araiza was the only Princeton hitter with multiple hits, going 3-for-5 with a double, an RBI and two runs scored.
David Garcia and Travis Flores homered while Garcia also walked twice, scored two runs and stole a base for Princeton (7-23).
Rodriguez and Rosario each finished 2-for-4 for Kingsport.
Venezuelan right-hander Andres Perez (0-1) took the loss in his first start after allowing five runs on six hits and three walks in 3 2-3 innings.
Kingsport, which has won eight out of its last 10, returns home Tuesday to start a three-game set with Elizabethton. First pitch at Hunter Wright Stadium is set for 7 p.m.
The K-Mets trail the Twins by 1½ games in the West Division and are four back from first place Greeneville.